A number of alkyl-5-substituted-3-furoate compounds of the kind provided by the process of the present invention are useful intermediates in the production of synthetic pyrethroid insecticides. In particular, ethyl-5-benzyl-3-furoate is a useful intermediate in the preparation of 5-benzyl-3-furyl methyl 2,2-dimethyl-3-(2-methylpropenyl)cyclopropanecarboxylate, a general purpose insecticide more commonly known by the generic name Resmethrin.
U.S. Pat. No. 3,465,007 to Elliott discloses many such synthetic pyrethroids modeled on the naturally occurring insecticide pyrethrum. The disclosed compounds are esters prepared by esterifying chrysanthemic acid or pyrethric acid with alcohols, such as 5-benzyl-3-furylmethyl alcohol.
U.S. Pat. No. 3,466,304, also to Elliott, discloses a method of preparing furan-substituted methanols by a complex synthesis, from a substituted-cyano compound condensed with an appropriate ester of succinic acid or succinic acid derivative.
U.S. Pat. No. 3,567,744 to Tanaka, et al., also shows a process for producing furoic acid derivatives. In addition to the claimed method which reacts 2-halo-5-halomethyl-3-furoic acid derivatives with an aromatic or heterocyclic compound, the reference details other methods then known to the art.
U.S. Pat. No. 3,755,368 to Huber shows a method for the preparation of 2-formyl esters involving the reaction of carboxylic compounds with carbon monoxide, preferably under pressure.
Japanese Pat. No. 137971/75 to Kondo and Matsui shows a method for the production of 5-benzyl-furan-3-carboxylic acid derivatives. The product compounds are the dehydrated condensation products of alpha-substituted hydrocinnamaldehydes and beta-keto acid esters.
The production methods in these references have all been more or less successful from a technical standpoint. However, problems with low yields, cost and availability of starting materials as well as the possibility of discovery of new and more effective pyrethroids have resulted in research into alternative synthesis.